Piston-valve



(No Model.)

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UNITED STATES PATENT "tries,

PISTONVAL.VE.

SPECIFICATON forming part of Letters Patent No. 323,410, dated August 4,1885.

[No model.)

T0 @ZZ whom t may concern:

Be it known that l, FREDERICK Fosmoi, of Fitchburg, county of Torcester7and State of Massachusetts, have invented an Improvement inPiston-Valves, of which the following description, in connection withthe accompanying drawings, is a specification, like letters ou thedrawings representing like parts.

My invention, relating to piston-valves for steam-engines, is shown asembodied in an engine havingavalve-gear, cylinder, and steamchest suchas shown in Letters Patent No. 279,404, granted to me June l2, 1883, thesaid patent showing independent piston-valves controlling inlet-ports atthe ends of the cylinder, and being themselves operated by a wrist`plate valve-gear.

XVhen piston-valves are employed, it is desirable to provide means foradjusting the said valves diametrically, so that they may be made to ittheir valve-cylinders after the surfaces have worn away, and suchadjustment has heretofore been provided for in some cases by making theperiphery of the valve as a cylindrical shell split longitudinally atone side and having a tapering bore at its inside cooperating with atapering plug, which by its longitudinal movement expands the shell tocompensate for the part worn away, thus causing it to nt the cylinderproperly. I have found that the valves of this class having anexpansible outer shell become expanded when in operation by the pressureof steam within the said shell, thus causing them to fit too tightly inthe cylinder, so as to produce a large amount of friction and require alarge pressure to move them. Such expansion of the valve is obviated inaccordance with the present invention by tapering the ends oi' theexpansiblc shell and giving to the heads of the valve a correspondingtaper, so that when the said heads are bolted tightly upon the ends ofthe valve the outer shell of the latter is positively locked in its adjusted shape and size, and cannot be expanded by internal steampressure.Vhen it is to be expanded by the tapering plug for the purposes ofadjustment, the heads are first loosened, and then, when the valve isproperly adjusted, they may again be bolted tightly upon the endsthereof to prevent l'urther expansion.

In engines employing a governor by which the valve-actuating eccentricis moved across the shaft to change the point of cut-off, and thuscontrol the power applied to the engine, the travel of the valve isdiminished as the point of cut-off is made earlier and its speed ofmovement is reduced, sol thata less extensive opening is aiiorded for admission of steam to the cylinder, and the steam is likely to bewire-drawn or to enter the cylinder at a less pressure than in the steamchest and boiler. This is obviated in accordance with the presentinvention by providing a longitudinal passage in the periphery of thepiston-valve, so arranged with relation to the inlet-port of thecylinder and to the passage in which the valve travels that when thesaid valve begins to uncover the port and admit steam over one edgethereoi` the said passage will connect the inlet-port with thesteam-spaces at the other side thereof, thus admitting steam from bothsides of the inlet-port simultaneously and giving double the openingthat would be obtained by a piston-valve without such longitudinalpassage.

Figure l is a plan view, partly in section,of a portion of an enginecontaining valves embodying this invention; Figs. 2 and 3, lougitudinalsections on lines .t fr and y y, respectively, of Fig. et of the valveproper on a larger scale; Fig. a, an end view of the said valve, andFig. .3 a transverse section thereof on line e, Fig. 3.

The chest a containing live steam, theinletports b b,leading therefromto the ends of the cylinder, and the valve -gear, a portion of which isshown at c c', for operating the valvestems d d connected with thevalves e e', may all be of usual construction, being connected in thisinstance substantially the saine as shown in my former patent referredto, the steamchest containing passages fj", connecting the steam-spacesat opposite ends of each of the valves e e, so that the pressure on thesaid valves is balanced independently, as described in the said patent,and the valvestem d being tubular and surrounding the stem d.

The valves e e', as shown in Figs. 2 to 5,

vare composed of an outer shell, g, split longitudinally at one side, asshown at 2, and having its interior made tapering, as shown in Figs. 2and 3, and containing a bushing, 71., which is also longitudinallysplit, preferably I held in proper relation to each other and joinedwith the valve-stem d or d by means of a sleeve, 7c 7c', fitted upon thevalve-stein and sccurely held. thereon between a projection or shoulder,d?, on the said stem and nuts d, the said sleeve being made in two partsto enable it to be insert-ed in the plug fi from opposite ends thereof.The part 7c of the sleeve is provided with a flange or head, k2, whichoverlaps the end ofthe shell g, the joint between the end of the shelland the head being made tapering or inclined, as shown, so that when thehead is prcssed'tightly upon the end of the shell it locks, thelatterpreventingit from expanding further. The other end ofthe valve isprovided with a corresponding head, k, free to slide longitudinally upona flange on the portion k', and the said head 7c is drawn toward thehead k2 to embrace and tightly hold the shell g between the said headsby means of bolts m (see Fig. 3) passing longitudinally through the plugil. The head k and adjacent end of the shell g are tapered the same asthe head k2, so that when the said heads are drawn tightly together uponthe shell they lock the latter securely from expansion.

The plugz' is moved longitudinally to eX- pand the shell and adjust thediameter of the valve by means of bolts and set-screws n n passingthrough the head k and engaging the adjacent end of the said plug, whichthus may be moved to a greater or less distance from the said head k,this being done While the bolts m are loosened, and when the said boltsare subsequently tightened, drawing the head k3 toward the head 7a2, theplug 1J will wedge into the shell g, expanding the same until it isengaged and locked by the two heads bearing solidly againstit, when thesaid heads constitute a locking device, preventing the shell fromexpanding further or away-from the plug i.

The shell f/ is provided with a longitudinal passage, o, just within itscircumference, as best shown in Figs. 3 and 5, the portion of theperiphery of the valve-shell which the said passage underlies beingsupported by bridges o', Figs. 2 and 5. The said passage operates, asbest shown in Fig. 2, to admit steam from the side of the steam-chesttoward which the valve is moving in opening or uncovering the inlet-portb through the said passage to the port b and cylinder, as

shown at 2, at the same moment that the valve uncovers the opposite edgeof the port at 3, admitting steam directly from the steam-chest, thusaffording double the width of opening for the admission of steam thatwould be provided if the valve did not have the passage o and controlledthe admission of steam only over the edge 3 of the port.

The length of the passage o is proportioned to that of the bridgebetween the port b and the edge 2 of the cylindrical passage in whichthe valve operates, so that the valve admits steam at 2 and 3 at thesame moment.

Both valves e e are the same in construction, and have the same relationto the ports controlled by them, and the valve e is fixed upon the solidrod din the same manner that the valve eis lixed upon the tubular rod elsurrounding the rod d. y

Access may be had to the nuts of the fasteningbolts m and the adjusting-bolts and screws a a', for the purpose of adjusting the valves whenthey have worn loose by removing Vthe heads or bonnets c of thesteam-chest, Which is shown in Fig. l, with one bonnet thus removed.

I claiml. In a piston-valve for steam-engines, the combination, with anexpansible shell having tapering or conical ends and tapering plugcooperating therewith, of heads engaging the ends of the said shell, thefaces of the said head which engage the ends of the said shell beingtapering, whereby the shell, when adj usted by the plug, is preventedfrom further expansion, substantially as described.

2. In a steam-engine, the steam-chest a, having ports b b2 leadingtherefrom to the cylinder and steam-passages connecting the steamspacesat opposite ends of the valve-heads, combined with a piston-valve actedupon at each end by live steam, the valve being provided with openingssurrounding itat diiterent portions of its length, such openings beingunited by longitudinal passages o, whereby steam is admitted alternatelyinto the ports b b at two places simultaneously, substantially asdescribed.

3. The expansible shell and expanding device for adjusting the same asto external diameter, combined with the locking device positivelyengaging the said shell; preventing further expansion thereof after thesaid shell is properly adjusted, substantially as described.

In testimony whereof Ihave signed my name to this specification in thepresence of two subscribing witnesses.

' FREDERICK FOSDICK.

Vitnesses:

WILLIAM E. SHELDON, E. P. SPARROW.

ICO

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